Article 01-22-1 is being republished in its entirety to update the vehicle model years and service procedures.

ISSUE:

Some dedicated Compressed Natural Gas (CNG) vehicles may exhibit a temporary Rough Idle, Hard Start, or No Start when the engine is cold. The condition may be most noticeable on the first start of the day, and during the first cold days of Fall or Winter.

ACTION:

Perform normal diagnostic procedures per the appropriate PC/ED manual section 2 Diagnostic Methods. If it is identified that the injectors are partially or completely clogged, then perform the following service procedure to clean the CNG injectors. Clean the CNG fuel injectors using Motorcraft PM-5 Power Flush Injector Fluid.

SERVICE PROCEDURE

NOTE:

THIS PROCEDURE SHOULD ONLY BE PERFORMED BY A CERTIFIED CNG TECHNICIAN.

NOTE:

FOLLOW ALL FUEL SYSTEM SAFETY PROCEDURES LISTED IN THE WORKSHOP MANUAL SECTION 303-04 FUEL SYSTEM PRECAUTIONS.

INJECTOR CLEANING PROCEDURE

NOTE:

IF THE VEHICLE WILL NOT START, GO DIRECTLY TO THE “VEHICLE NO START PROCEDURE”

Start vehicle and idle for 5 minutes, then turn engine off. The cleaning fluid is more effective with a warm engine.

Start engine and run at idle for 30 seconds, turn engine off, wait 5 minutes allowing the cleaning fluid to remain in the injectors.

Repeat Step 6 one time.

Test Drive Vehicle to verify that the Rough Idle condition is corrected. VEHICLE SHOULD BE DRIVEN IMMEDIATELY FOR AT LEAST 10 MINUTES TO ENSURE CLEANING FLUID IS FLUSHED OUT OF FUEL SYSTEM.

NOTE:

IN SOME CASES, IF ROUGH IDLE REMAINS DUE TO TOUGH CLOGGING OF INJECTORS, REPEAT THE INJECTOR CLEANING PROCEDURE STEPS 1-8. IF ROUGH IDLE STILL REMAINS, FOLLOW THE “VEHICLE NO START PROCEDURE”.

After all injector cleaning and other service is completed, drain the CNG Coalescent Filter Bowl, replace coalescent filter element, drain plug and bowl O-ring using Part Number F5TZ-9365-AA. Re-pressurize fuel system and leak test.

VEHICLE NO START PROCEDURE

If vehicle will not start due to Clogged Injectors, the injectors may be completely stuck closed. Attempt to free the injectors by applying 12 Volts directly to the injector coil.

NOTE:

DO NOT APPLY VOLTAGE TO THE INJECTOR FOR MORE THAN “TEN SECONDS” OR INJECTOR DAMAGE MAY RESULT.

Apply battery voltage to the red wire (circuit 361) side of the injector connector. Ground the other side of the injector connector momentarily and listen for an AUDIBLE CLICK to confirm that the injector has opened. Continue with Step 1 of the “INJECTOR CLEANING PROCEDURE”.

NOTE:

IF AN INJECTOR REMAINS STUCK (NO AUDIBLE CLICK), WAIT 10 SECONDS AND REPEAT STEP 2 OF THE “VEHICLE NO START PROCEDURE”. IF AN INJECTOR DOES NOT PRODUCE AN AUDIBLE CLICK AFTER THREE ATTEMPTS REPLACE THE INJECTOR PER “INJECTOR REPLACEMENT PROCEDURE”.